This proposal has been oriented to study, in detail, the slime polysaccharides of various strains of Pseudomonas aeruginosa. The slime polysaccharides will be extracted, purified, and characterized in regard to chemical, immunochemical, and biologic properties. Characterization of the biologic properties will define toxicity, role in experimental infection, and ability to induce protective antibodies. Further characterization of each of the purified polysaccharides will be accomplished by chemical and more selective enzymatic cleavage, utilizing specific phage-induced depolymerases. The fragmented moieties will be analyzed to delineate the characteristics of the antigenic and toxic determinants. These analyses will provide useful criteria for determining the relationships which exist between the various polysaccharides and establishing a chemical basis for the heterogeneity which has been observed amongst various strains of P. aeruginosa. Ultimately, this study will provide an understanding of the role of these polysaccharides in the infectious process and detailed information regarding their ability to function as protective antigens in man.